Repulsion-motor control.



PATENTED' OCT. 9, 1906.

2 SHEETS-SHEET 1.

Fig.1.

Inventor.

Witnesses.

Maurie Milch.

PATENTED OCT. 9, 1906.

M. MILCH. REPULSION MOTOR CONTROL.

APPLICATION nun APR. 30, 1904. RENEWED rm. 9, 1906.

2 SHEETS-SHEET 2.

Fi g6.

nventor Maurice Miich Witnesses.

-new and useful Improvements in Re -short circuit and; to tion at'an angle to sai short circuit.

UNITED STATES PATENT OFFICE.

- MAURICE MILCH, OF SUHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

HEPULSION -MOTOR CONTROL.

Io. saanar.

Specification of Letters Patent.

Patented 08'. 9,1006,

Application April 80, 1904. Renewed February 9,1906. Serial No. 800,821.

Motor Control, of which the following is a specification.

My invention relates to alternati -current motors of the type known as repu sion, in

which single-phase current is supplied to the member, while the secondary memr is s ort-circuited by' means of a commutator and brushes, the motor being arranged and connected to induce a current in the reduce a magnetiza- The object of my invention is to enable such motors to beoperated without sparking at the commutator over much wider ranges of'speed than has been possible heretofore. It has been foundin practice that While repulsion-motors show practically no sparking at .s eds near synchronism very violent spar 'ng results if the motor speed is carried a certain amount above synchrcnism.

- By my invention I render it possible to operate repulsion-motors'at all speeds, both above and below s rious sparking at t e'commutator.

My invention will best be understood by reference to the accompanying drawings, in which v Figure 1 shows diagrammatically an arrangement embodying my invention. Figs;

, 2 and 3 are explanatory diagrams, and Figs; 4, 5, and 6 show modifications of the arrangement of Fig; 1

Referring first to Fig. 2, S represents diaammatically the stator or primary memer of an alternating-current motor su plied with single-phase current so as to pro uce a magnetization indicated by the arrow F. R represents the rotor, short-circuited by means of the commutator-brushes b b on a line at an angle to the'line of'the primary field F. The current in rotor R produces a cross-field F in phase with the rotor-currents. It is this field which reduces the motor tor ue. If

ii rushes the rotor-co s short-circuited by the b b are considered, it will be seen that they are subject to two sources of electromotive siouchronism, without injuforce. In the first (place, an electromotive tromotive forces are shown in Fig. 3.' Thus if E represents the primary impressed electromotive force, F represents the primary m etization ninety degrees out of phase wit the impressedelectromotive force E. F represents the cross-field, due to the rotorcurrents. Near synchronism the rotor-currents are nearly in phase with or in opposition tothe primary impressed electromotive force, and consequently the field F, which is in phase with the rotor-currents, may be represented as practically in phase with the prisaid that the short-circuited coils are subject to two electromotive forces induced by cutti the field F and by transformer action from t e field F. Thus the electromotive force due to cutti the field F is represented by a line e in opposition to field F. The electromotive force induced by transformer action by field F is represented b a line e ninety de ees out of phase with t e field F.

j From t e foregoing it will be seen that the electromotive forces e and e are nearly in 0 position and nearly e ual at s chronism.

mary electromotive force E. It has been onsequently the, resu tant e ectromo tive force in the rotor-coils short-circuited by the brushes is very small at synchronism, which is the reason why tactically sparkless operation is obtained s eeds. As the speed of the motor increases a ove synchronism, however, the electromotive force 6, due to cutting the field F, will increase, owing to the eater speed of rotation, while, on the other and, the electromotive force e, induced by transformer action by .field F, will smaller, since the rotor- -currents decreasein. strength. The electromotive force 0 will consequently overpower the electromotive force e, hea currents will flow in the rotor-coils short-crrcuited by the brushes, and violent sparking will result. Now if it were possible to reduce the value of the electromotive force 0 or to increase the electromotive force e it is evident that the sparking would be reduced. The electromoat nearly synchronous tive'forcev e can bereduced by reducing the field F or, in other words, by reducing the imlpressed electromotive force to which the so that the gain would be small.

d F is due but'sim 1y reducing the impressed electromotive bdrce would decrease the output of the motor, and, furthermore, the rotor-currents, and consequently field F and electromotive force e, would also be reduced,

My invention'consists in compensating for the reduced primary impressed'electromotive force by impressing upon the/rotorbrushes an electromotive force of the proper amount to compensate for the reduced primary 1n output 0 the motor at its normal, value. By this means the. electromotive force e may be reduced at speeds above synchronism Without reducing the rotor-currents and the electromotive force 6 and sparkless operation of the motor obtained Without impairing the 7 output of the motor.

Referring now to Fig. 1, S represents dia-- nal to'a terminal of the autotransformer T.

shown in dotted lines. .thereby .short-circuited, and the The other terminal of transformer t is connected to the movable contact of the au-' totransformer T. The operation isthen .as follows: The movable contact of trans-' former T is placed so as to impress upon the stator-winding S a voltage suitable for starting, while switch 8 is moved to the position Transformer t is rotorbrushes are consequently short-circuited. The motor therefore starts as an ordinary repulsionmotor' and may be brought u to speed b shiftinlg the movable contact 0 au totrans ormer As synchronous speed is reached the movable contact may be placed so as to impress the full-line voltage upon the stator-winding and switch 8 may be ines removing the short circuit""fromvariablefop- 1 erations of the moved to the position shown in 'full In this position of switch 8 transformer-t and consequently brushes 6 b are still short-circuited. Now if it is desired to operate the "motor above synchronism the movable contact of transformer T may be moved to re-- duce the electromotive force impressed upon the stator-winding S. This movement of the movable contact will at the same time introduce an impressed electromo tive force upon the primary of transformer t',"which if transformer tis properly proportioned will ut, and thereby to maintain the 2 uld' be ioo cuited'.

this arrangement I haveshownthe con impress upon'the rotor bi'ushes b anelectromotiveforce, of theproper amount to compensate for the reducedamount of "en-' ergy supplied tothe'statomwinding, thereby maintaining the output of the motor at its normal value.

; Fig. 4 shows an arrangement in which the '70- secondary of. a shunt-transformer if Ithroiwh movable contacts, so a ranged; that not only may the impressed electro motive' fermion the brushes be varied, but .also'the'direction of 'electromotive force be reversed; Thi'sfar- I'nent is particularly well'adafi tedforoprange eration below synchronism as we asabove. At starting, an electromotivef fo e ,r'n'ay be impressed upon the rotor brush'es opposing, the electromotive force ind'uced'i'irthe ing by the starting-field,Qfllie'lam starting-current in'this ma tm 'erilim d. to its proper value. As the mot-or eedgju this counter electromo'ti'v forceis red (fled until at or near synchronous speed thero.tjor'--' brushes are short-circui'ted.f For/speeds above synchronism an electromotiveforc'e is again impressed upon'the' rotor-brushesb b,

' but opposite in direction to that'impressed at starting." This el'ectromotiv'e force supplies to the rotor an electromotive foice proper phase and amount tojpi'e'vent voltage on the primary the me er;- greater above synchronismthanfit' 1f the primary'i'mpressed' voltage were reduced.

Fig. 5 shows another arra ngement in ivliiicl1 the rotor-brushes b b areiconnected tbthe-see ondary of aseries transfornierf't pwhich is I05.

provided with a movable contact, sbithht more or less of the primary may be short-cir- A't starting, the entire riinary of transformert may be short circuitedf here:

the starting-current of" theinotormaybe regulated by the autotransformer Tff For speeds above s nchron'ism the proper lectromotive force 0 the rotor may-bejobtained by primary or series pensioner l may be employed,-v as sl1own' iriFig1i6 tions between the fconmiutator-brushesand 1 the secondary of transfonn'er i arranged tb permit of reversal as ivell as variation 0 he electromotive'force impressed" upon brushes. Controlby mani pun rotor-circuit may'thusibe obtained; shown 1 in Fig. 4, and I have'also 's'hownin this "arby short-circuiting the rotor-trustee I) bi, and l re In the same way a s'h'iint ltran sforirier lit l n N rangement the autotransformer T control-' ling the primary circuit, and thereby permitting the motor to give approximately the same output above synchronism as if the motor were operated'in the usual way with constant .primary voltage and short-circuited secondary.

Many other arrangements v of the transformers or voltage-regulators may be employed in carrying 'out my invention with either manual or automatic control. Accordingly I do not desire to limit myself to the particular construction and arrangement of parts here shown, since changes which do not depart from the spirit of myinvention will be obvious to those skilled in the art.

I have defined a repulsion-motor above as an alternating-current motor of the type in which single-phase current is supplied to the primary member, while the secondary memer is short-circuited by means of commu tator and brushes, the motor being arranged and connected to induce current in the,short circuit and to produce a magnetization at an angle to the short circuit. It is with. this meaning that I employ the term repulsionmotor in the appended claims, and I desire it to be understood that this term embraces both arrangementsin which the field which induces current in the short circuit and the field at an angle thereto are produced by the same set of connections or coils and motors in which these two fields are produced by dif-- ferent sets of connections or by different windings.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The method of improving commutation of a repulsion-motor at speeds above s nchronism, which consists in reducing the e ectromotive force impressed on the primary member, and impressing a compensating electromotive force on the secondary member. 1

2. The method of improving commutation of a repulsion-motor for varying speeds, which consists in impressing on the secondary member an electromotive force variable in ma itude and in direction.

3. he method of improving commutation of a repulsion-motor for varyin speeds, which consistsin impressing an e ectromotive force on the secondary member at start ing, reducing said electromotive force as the motor speeds up, then reversing the electromotive force when the motor asses s nchronous speed, and then increasing the e ectromotive force as the motor speed further increases.

4. The method of improving commutation of a repulsion-motor for operation above synchronism, which consists in impressing on the secondary member when the motor passes ta'tion of a repulsion-motor for operation abovesynchronism, which consists in impressing on the secondary member when the motor passes above synchronous speed an elect omotive force op osing the electromo-- tive force induced t e secondary coils by cutting the rimary field and increasing said impressed e ectromotive force as the motor speed further increases. a

6. The method of improving the com tation of arepulsion-motor for operation above synchronism which consists in impressing upon the secondary member an electromotive force assisting the electromotive force induced in the secondary coils by transformer action by the primary field.

7. The method of improving commutation of a repulsion-motor at speeds above synchronism, which consists in impressing an electromotive force on the secondary member and varying the electromotive forces impressed on the primary and secondary mem ersas the motor speed varies.

8. The method of improving commutation of a repulsion-motor at speeds above synchronism, which consists in reducing the primary impressed electromotive force, and 1mpressing on the secondary member an electromotive force. adapted to compensate for the reduced input to the primary.

9. The method of improving commutation of a repulsion-motor for varying speeds, which consists in maintaining an approximate balance of the electromotive forces in the rotor-coils short-circuited by the brushes induced by cutting the rimary field and by transformer action of t e crossfield respec-- tively.

10. The method of im roving commutation of a repulsion-motor fbr var ing s eeds, which consists in varying t e re ative strengths of the primary field and of the cross-field so as to maintain an approximate balance of the electromotive forces induced by said fields in the rotor-coils short-circuited by the brushes.

11. In combination with a repulsion-motor, means for impressing on the secondary member of said motor an electromotive force variable in magnitude and in direction.

12. In combination with a'repulsion mo--' tor, means for impressing a variable electro: motive force on the secondary member of said motor, and means for var ing the primary impressed electromotive orce. v

13. In combination with a repulsion-motor, means for im ressing an electromotive force on the secon ary member of said motor,

and means for simultaneously varying the with Varying speeds of the motor to mainprimary and secondary impressed elgmtrotain an approxlmate balance of the clc'cnromotive forces. motive forces induced b said fields inqt he 14. In combination with a repuls ion-morotor-coils shortcircuite by the brushes. I 5 tor, 4regulatingtmnsforn1ers. connected rln'witness whereof I have hereunto set, my 1 5 l I spectively-to theprimary and secondary hand this 29th day of A ril, 1904." v I I members of said motor. I 3 MAKURIGEDLMILCHJ'.

15.. In combination with a repulsion m0- Witnessesz' I; l tor, means for'varying the' relative stren ths BENJAMIN B. HULL, roof th'ejprimary field and o'fc'the crosseld, HELEN ORFoRn. I 

